Tektronix 1L30, Instruction Manual

Page: 72 / 129

C«Ubr«iian— Typo • 0
Fig. 6-16. Equipment setup to adjust avalanche voltage, 1 MHz internal reference frequency and check 1 MHz to 5 MHz external reference
frequency range.
PHASE LOCK CIRCUIT
Type 1L30
POS Position a free running
trace to the bottom
line of the graticule
IF CENTER FREQ Midrange (000)
FINE Centered
DISPERSION RANGE M H z /C M
DISPERSION 5 MHz
VIDEO FILTER OFF
G A IN Midrange
VERTICAL DISPLAY LIN
IF ATTEN Switches off
FINE RF CENTER FREQ
Centered
IN T 1 M H z REF FREQ OFF
Oscilloscope
Tim e/Cm 10 ms
Triggering Adjusted for a free
running sweep
Centered trace
8. Adjust Avalanche Voltage and the 1 MHz 0
Internal Reference Oscillator
a. Equipment setup is shown in Fig. 6-16.
b. W ith the INT 1 M H z REF FREQ switch in the OFF posi­
tion, depress the LOCK CHECK button and adjust the
Avalanche Volts adjustment R831 (Fig. 6-17) clockwise until
avalanche occurs, then ccw from this point about ’/ 8 turn.
Free running avalanche appears as a wide, noise trace or
a definite increase in the noise level on the trace. See
Fig. 6-18. Turn the adjustment Vs turn counterclockwise
from the free running state.
NO TE
It is not uncommon to have instruments in w h ic h
this circuit may not free run even with the a d ju s t­
ment fu lly clockwise. If this occurs, set the adjust­
ment a p p ro xim a tely 2 0 ° back from the full clock­
wise position.
c. Apply a 5 M Hz signal from the Signal G enerator
through a T connector to the EXT FREQ IN connector. Con­
nect the test oscilloscope to the T connector, so that the
input signal amplitude to the Type 1L30 can be monitored.
d. Adjust the Signal G enerator output for a 1 volt peak
to peak 5 MHz signal. Check for the presence of phase-
Horizontal Position